USB is slow on nForce4 chipset variants

[hbayindir@ada.net.tr]

Hi all,

I'm runnig debian lenny on my current notebook (HP DV6187EU) which sports
a dual core Turion64 x2 CPU @ 1.8GHz with 2GBs of RAM. Whole hardware runs
on nVidia MCP51 chipset. Also, my older computer (which ran lenny until I
changed it with a quad core Intel) sports a Athlon64 3700+ @ 2.2 GHz with
2GBs of RAM and runs on nVidia nForce 4 ultra.

Both of these computers exhibit a very annoying problem. Their USB2.0
drives are slow when compared to windows ran on the very same computer.
First, I know that nVidia's USB performance is not that great when
compared to Intel ICH8/9 but the speed difference between windows and
linux is still annoying on these platforms.

Is anybody having the same problem? If yes, does anybody has a solution? I
intend to chase this bug so if anybody can point to somebody directly I
can contact with him/her. If nobody knows anything, I'll again dig kernel
sources but if you can light up first one or two squares it'll be enough.

Below is the benchmarks I've done on my notebook both in Linux and
Windows. The problem is present since I installed debian on my older
desktop and never healed even temporarily.

Tested kernel is 2.6.25-2. Debian Lenny package.

OCz Rally2 8GB (W-25,6/L-15,4) (Windows is %66 Faster)
Sandisk Cruzer Micro W/Skins 1GB (W-18,48/L-12,33) (Windows is %50 Faster)
Sandisk Cruzer Titanium 4GB (W-18,14/L-12,40) (Windows is %49 Faster)
Sandisk Cruzer Micro U3 W/ReadyBoost 8GB (W-25,7/L-15,36) (Windows is %67
Faster)

All speeds are MB/s, tests done with ATTO disk benchmark on windows and
hdparm on linux. hdparm has run 4 times and speeds are averaged.

Also please note that the speed difference is wider if the device is faster.

Thanks in advance,

Hakan.

P.S: The same problem is also present at least one laptop owner which also
runs a Turion64 x2 and nVidia chipset.